8 Weeks Of Instability Resistance Training Can Significantly Improve Pull-up Ability In Male College Students

Instability resistance training(IRT) has produced good results in lots of exercises, such as bench press and deep squats. It needs to be discussed whether the same effect can be achieved in pull-ups which has been included in the National Physical Fitness Test for college students in many countries. PURPOSE: To investigate the effects and potential mechanisms of IRT to improve pull-up performance in male college students. METHODS: 34 healthy male college students who can do at least 1 pull-up were equally divided into IRT (19 ± 6 yrs) and resistance training (RT)(18 ± 1 yrs) groups as study subjects. Based on the principle of specificity of training, subjects in both groups were required to do lat pull-down strength training interventions of 12 repetitions per set, 4 sets each time, 3 times per week, for 8 weeks. The IRT and RT groups separately completed tasks on an unstable and a conventional lat pull-down strength machine. Lat pull-down maximal voluntary isometric contraction peak force (MVIC), pull-up endurance (number of repetitions) and surface EMG signals of 8 upper and back muscles were recorded before and after the training intervention. Comparisons of variables were analyzed by 2-way ANOVA with repeated measures. RESULTS: After 8 weeks of training, pull-up endurance was significantly improved in the IRT (2 ± 1 vs. 8 ± 3, P < 0.01) and RT (2 ± 2 vs.6 ± 3, P < 0.01) groups, and the IRT group performed significantly better than the RT group (P < 0.05). Lat pull-down MVIC is significantly higher than pre-training in both IRT (679 ± 123 vs. 816 ± 112 N, P < 0.01)and RT (622 ± 127 vs. 774 ± 125 N, P < 0.01) groups. In terms of muscle activation, the EMG RMS amplitudes of agonist muscles (BB, BR, LD, PM and PD) decreased significantly in both groups after training, but there was no significant difference in the rate of decrease between the two groups. The EMG RMS amplitudes of antagonist muscles (TB, AD and MD) of the IRT group decreased by 16 ± 18, 25 ± 21 and 16 ± 14%, respectively, which were significantly superior to those of the RT group (-1 ± 25 ,4 ± 24 and 4 ± 39%). CONCLUSIONS: IRT is more effective than RT for male college students to finish more pull-ups after an 8-week training, which may be related to its ability to optimize neuromuscular synergistic control, reduce the level of antagonist muscle activation and improve the efficiency of muscle contraction.